Property, Plant and Equipment, Net Property, Plant and Equipment, Net - SPPC (Details) - Sierra Pacific Power Company [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 3,002	$ 2,962
Property, plant and equipment, net	3,143	3,075
Common Facilities [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	141	113
Property, plant and equipment, net	3,143	3,075
Regulated Operation [Member] | Electricity Generation Plant, Non-Nuclear [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation or Processing	1,129	1,133
Public Utilities, Property, Plant and Equipment, Transmission	911	840
Public Utilities, Property, Plant and Equipment, Distribution	1,724	1,669
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 187	178
Regulated Operation [Member] | Electricity Generation Plant, Non-Nuclear [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	25 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	50 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	20 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years
Regulated Operation [Member] | Electricity Generation Plant, Non-Nuclear [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Generation, Useful Life	60 years
Public Utilities, Property, Plant and Equipment, Transmission, Useful Life	100 years
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	100 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years
Regulated Operation [Member] | Natural Gas Processing Plant [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution	$ 424	417
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment	$ 14	14
Regulated Operation [Member] | Natural Gas Processing Plant [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	35 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	5 years
Regulated Operation [Member] | Natural Gas Processing Plant [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Distribution, Useful Life	70 years
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years
Regulated Operation [Member] | Common Facilities [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common	$ 344	338
Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress	4,733	4,589
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	1,733	1,629
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 3,000	2,960
Regulated Operation [Member] | Common Facilities [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	5 years
Regulated Operation [Member] | Common Facilities [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Common, Useful Life	70 years
Unregulated Operation [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress	$ 2	$ 2
Unregulated Operation [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years
Unregulated Operation [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life	70 years